High-resistance silicon wafer and process for producing the same

ABSTRACT

A high-resistance silicon wafer is manufactured, in which a gettering ability and economical efficiency is excellent and an oxygen thermal donor is effectively prevented from being generated in a heat treatment for forming a circuit, which is to be implemented on the side of a device manufacturer. In order to implement the above, a high-temperature heat treatment at 1100° C. or higher is performed on a carbon doped high-resistance and high-oxygen silicon wafer in which specific resistivity is 100 Ωcm or more and a carbon concentration is 5×10 15  to 5×10 17  atoms/cm 3  so that a remaining oxygen concentration becomes 6.5×10 17  atoms/cm 3  or more (Old-ASTM). As this high-temperature treatment, an OD treatment for forming a DZ layer on a wafer surface, a high-temperature annealing treatment for eliminating a COP on the surface layer, a high-temperature heat treatment for forming a BOX layer in a SIMOX wafer manufacturing process and the like can be used.

TECHNICAL FIELD

The present invention relates to a high-resistance silicon wafer used ina support substrate and the like in a high-frequency communicationdevice or an analog-digital device and its manufacturing method.

BACKGROUND ART

Recently, a demand for high-resistance substrate is increased along withthe widespread use of a high-frequency communication device used in ashort-distance wireless LAN. Conventionally, a compound semiconductorsubstrate such as GaAs has been mainly used as a support substrate of aRF (Radio Frequency: high frequency) circuit which requires highresistance. However, the compound semiconductor substrate is veryexpensive.

Meanwhile, a silicon CMOS requires a large amount of power, so that ithas been considered that it is not suitable for the RF circuit. However,because of recent considerable miniaturization and development ofdesigning, it can be applied to the RF circuit. Therefore, ahigh-resistance silicon wafer which is excellent in RF characteristicsand excellent in economical efficiency such as a mirror-surface siliconwafer and a SOI (Silicon On Insulator) wafer using high-resistancecrystal grown by the Czochralski method (CZ method) has attracted a lotof attention instead of the substrate of the compound semiconductor suchas GaAs.

In addition, there is a demand for improvement of a substrate resistanceto noise in an analog-digital device and in this view also there is ademand for a high-resistance silicon wafer.

However, since a quartz crucible is used when a silicon single crystalis manufactured by the CZ method, oxygen is contained in the crystal inan oversaturated state. Since an oxygen donor such as a thermal donor(TD) and a new donor (ND) is formed from this oxygen in a heat treatmentin the process of forming a circuit of the device, there is a bigproblem such that resistivity of the wafer unstably varies on the sideof a device manufacturer.

FIG. 1 is a graph showing a relation between the oxygen donor and thewafer resistivity. In a case of the normal low-resistance wafer to whicha dopant is added, since the oxygen donor slightly affects theresistivity of the wafer, there is no problem in a real operation.However, in a case of the high-resistance wafer in which the dopant islimited, when it is an n type, the resistivity is considerably reducedas the oxygen donor is increased. When it is a p type, although theresistivity is considerably increased along with the increase of theoxygen donor at first, if the oxygen donor is kept increasing, the ptype is converted to the n type, so that the resistivity is considerablydecreased.

In order to solve the above problem such that the resistivityconsiderably varies along with the increase of the oxygen donor, thereis taken measures to prevent the oxygen donor from being formed by usinga low-oxygen silicon wafer which is manufactured using a specialcrucible in which oxygen is prevented from being fused by a MCZ methodor an inner face SiC coating. However, the low-oxygen silicon waferwhich needs to use the MCZ method or the special crucible is surelyexpensive as compared with the general-purpose silicon wafer having arelatively high oxygen concentration which is manufactured by the normalCZ method. In addition, the oxygen lowering has a technical limitation.That is, in general, it is considered that concentration of 6×10¹⁷atoms/cm³ or less is difficult to be implemented and a degree of 8×10¹⁷atoms/cm³ is a limit in a wafer of 300 mm. In addition, in the siliconwafer having a low oxygen concentration, there is a problem of slippingand the like because of the lowering of mechanical strength caused byreduction in oxygen concentration.

In order to solve the above problem, International Publication WO00/55397 pamphlet discloses a technique in which a silicon singlecrystal rod having resistivity of 100 Ωcm or more and initialinterstitial oxygen concentration of 10 to 25 ppma [JEIDA] (7.9 to19.8×10¹⁷ atoms/cm³ [Old-ASTM]) is grown, and a heat treatment foroxygen precipitation is performed on a silicon wafer cut from the aboverod so as to limit the remaining interstitial oxygen concentration inthe wafer to 8 ppma [JEIDA] (6.4×10¹⁷ atoms/cm³ [Old-ASTM]) or less.

According to this technique, the manufacturing cost of the initial waferbecomes low because the general-purpose silicon wafer having a highinitial oxygen concentration is used. Although the general-purposesilicon wafer having the high initial oxygen concentration is used,since the oxygen precipitating heat treatment is performed on thesilicon wafer, the remaining oxygen concentration is lowered. Therefore,an oxygen donor is effectively prevented from being generated in a heattreatment for forming a circuit which is to be performed on the side ofa device manufacturer. In the process of lowering the oxygenconcentration in the wafer, a large amount of oxygen precipitate (BMD)is generated. Therefore, a gettering ability of the wafer is improved.

However, according to the technique disclosed in the InternationalPublication WO 00/55397 pamphlet, it is necessary to generate the largeamount of oxygen precipitate (BMD) using a high-resistance primarysubstrate having a high-oxygen concentration, and to sufficiently lowerthe remaining oxygen concentration of a product silicon wafer because ofgeneration of the large amount of oxygen precipitate (BMD). However,this causes the following problems.

First, to lower the remaining oxygen concentration in the productsilicon wafer causes the mechanical strength of the wafer to be lowered.This is clear from the fact that slip dislocation generated from a wafersupporting part in the heat treatment is fixed by oxygen and as aresult, a slip length is lowered as the oxygen concentration isincreased [M. Akatsuka et al., Jpn. J. Appl. Phys., 36 (1997) L1422].Meanwhile, the oxygen precipitate (BMD) is a factor of affecting thestrength. The influence of BMD to the strength is complicated. Forexample, when the heat and stress of one's own weight added to the waferis not so large, the movement of the slip dislocation is prevented andthe strength is improved (International Publication WO 00/55397), butwhen the heat and the stress of one's own weight is large, the BMDitself becomes a source of the slip dislocation, so that the strength islowered and the wafer is probably warped (K. Sueoka et al., Jpn. J.Appl. Phys., 36 (1997) 7095). The heat and the stress of one's weightapplied to the wafer in the real device process depend on a devicestructure or a thermal sequence, and it is expected to be increased insome cases. Therefore, in view of maintaining the mechanical strength ofthe wafer, if the BMD required for gettering is provided, theconsiderable lowering of the remaining oxygen by the excessive BMDgeneration described in the International Publication WO 00/55397 is notpreferable.

The second problem is a heat treatment cost. That is, in order togenerate a large amount of oxygen precipitate, the heat treatment forforming the oxygen precipitate nucleus and the heat treatment forgrowing the oxygen precipitate at a high temperature for a long time areneeded. Therefore, the heat treatment cost is increased. As a result,although the manufacturing cost of the primary wafer is inexpensive, aprice of a final product wafer becomes expensive.

It is an object of the present invention to provide the high-resistancesilicon wafer in which a gettering ability and economical efficiency isexcellent, the oxygen donor is effectively prevented from beinggenerated in the heat treatment for forming the circuit which is to beimplemented on the side of the device manufacturer, and mechanicalstrength is high, and its manufacturing method.

DISCLOSURE OF INVENTION

In order to attain the above objects, the inventors of the presentinvention have determined that a cause of the above problems lies in theexcessive generation of the oxygen precipitate (BMD) and theconsiderable lowering of the remaining oxygen concentration in theproduct wafer caused by the excessive generation thereof, and studiedabout measures for preventing the generation of oxygen donor instead ofthe generation of the oxygen precipitate (BMD) in the high-resistancesilicon wafer. As a result, they discovered that carbon doping iseffective in preventing generation of the oxygen donor, especially inpreventing generation of the thermal donor, and when a heat treatment isperformed in addition to the carbon doping, the generation of the oxygendonor such as the thermal donor and a new donor is more effectivelyprevented, and many existing heat treatments which are generally used ina process of manufacturing various kinds of wafers such as a DZ wafer, ahydrogen annealed wafer, a SIMOX type and a bonded type of SOI wafer canbe used as the heat treatment which is effective in preventing thegeneration of the oxygen donor.

The fact that the carbon doping is effective in preventing thegeneration of the oxygen thermal donor is well known in a wafer having anormal resistance in which resistivity is less than 100 Ω (for example,refer to A. B. Bean and R. C. Newman J. Phycs. Chem. Solids, 1972, Vol.33, pp. 255-268). However, in order to prevent the generation of theoxygen thermal donor in the wafer having the normal resistance, a carbonamount needs to be 1×10¹⁸ atoms/cm³. Since such carbon doping at highconcentration accelerates dislocation in the growth of the singlecrystal by the CZ method and its crystallization becomes difficult, itis not realistic measures. However, it has become clear that in ahigh-resistance wafer having resistivity 100 Ω or more, an amount ofcarbon needed for preventing the generation of the oxygen thermal donorcan be lowered to a realistic level such as 5×10^(l5) to 5×10¹⁷atoms/cm³ which does not hinder the single crystal crystallization.

Thus, since the appropriate amount of carbon doping in thehigh-resistance wafer can effectively prevent the generation of theoxygen donor in the heat treatment for forming the circuits which is tobe implemented on the side of the device manufacturer, it becomesunnecessary to excessively generate the oxygen precipitate (BMD), sothat the heat treatment cost can be lowered. In addition, it is notnecessary to considerably lower the remaining oxygen concentration inthe product wafer, so that the mechanical strength of the wafer can beimproved. Furthermore, as described in a document (M. Akatsuka and K.Sueoka, Jpn. J. Appln. Phys., 40 (2001) 1240), further improvement inmechanical strength can be implemented by the appropriate amount ofcarbon doping. In addition, since generation of dislocation cluster whenthe single crystal is grown can be prevented by the carbon doping,non-defect crystal region in the growth of the single crystal can beexpected to be enlarged.

The reason why the carbon doping is effective in preventing thegeneration of the oxygen thermal donor is thought as follows. Inaddition, the reason why the doping amount of carbon can be reduced inthe high-resistance wafer is thought as follows. Still further, thereason why the generation of the oxygen donor is prevented by the heattreatment of the carbon doped wafer is thought as follows.

Although the reason why the carbon doping is effective in preventing thegeneration of the oxygen thermal donor is not completely figured out,according to A. B. Bean and R. C. Newman J. Phycs. Chem. Solids, 1972,Vol. 33, pp. 255-268, for example, the reason is thought as follows.That is, the oxygen thermal donor is an On cluster in which 4 to 20oxygen atoms are collected and it is generated at 400 to 500° C. When acarbon atom exists at an early stage of generation of such cluster, thecarbon is captured by O₂ cluster which is a precursor to an electricallyinactive thermal donor and C—O₂ cluster is generated. Therefore,subsequent generation of the electrically active On (n≧4) can beprevented.

In addition, in the silicon wafer having a normal resistance such asseveral Ωcm to several tens of Ωcm, it is necessary to generate thethermal donor of 10¹⁴ to 10¹⁶ atoms/cm³ in order to detect thegeneration of the oxygen thermal donor by variation of resistivity, anda high-concentration carbon such as 1×10¹⁸ atoms/cm³ is needed in orderto prevent the generation of the thermal donor having such density.However, in the case of the high-resistance silicon wafer havingresistance of 100 Ω or more, since resistivity is varied by thegeneration of the oxygen donor of 10¹⁴ atoms/cm³ or less, the carbondoping amount to prevent this generation can be reduced to 5×10¹⁵ to5×10¹⁷ atoms/cm³.

In addition, it was found that when a heat treatment at 1100° C. or morewas performed on the high-resistance silicon wafer having resistance of100 Ω or more in which carbon was doped, the generation of the oxygendonor could be effectively prevented. Although the reason why thegeneration of the oxygen donor is prevented by the heat treatment at1100° C. or higher and carbon doping is not clear at present, it isthought that the thermal donor which is a relatively small oxygencluster and the new donor which is regarded as an initial form of theoxygen precipitate which is generated in the heat treatment at 600 to700° C. are grown, or decomposed and inactivated in the heat treatmentat 1100° C. or higher.

The high-resistance silicon wafer of the present invention is completedbased on the above knowledge and it is a CZ silicon wafer havingresistivity 100 Ω or more, in which a carbon concentration is 5×10¹⁵ to5×10¹⁷ atoms/cm³.

In addition, according to a manufacturing method of the high-resistancesilicon wafer of the present invention, a heat treatment which iseffective in preventing the generation of the oxygen donor, andpreferably a high-temperature heat treatment at 1100° C. or higher isperformed on the silicon wafer having the resistivity of 100 Ω or moreand a carbon concentration of 5×10¹⁵ to 5×10¹⁸ atoms/cm³.

Since the carbon concentration in the high-resistance silicon waferaccording to the present invention is 5×10¹⁵ to 5×10¹⁷ atoms/cm³, thegeneration of the oxygen thermal donor can be prevented while theremaining oxygen concentration is maintained at high level, and themechanical strength and the slipping resistance of the wafer can beimproved by the high-concentration remaining oxygen and the carbondoping. In addition, excellent gettering ability can be provided by thegeneration of an appropriate amount of oxygen precipitate (BMD) which isnot influenced by the remaining oxygen concentration.

When the carbon concentration in the wafer is less than 5×10¹⁵atoms/cm³, the effect in preventing the generation of the oxygen donoris not sufficient. Meanwhile, when it is more than 5×10¹⁷ atoms/cm³,dislocation could occur while the crystal is grown and single crystalcrystallization becomes difficult. An especially preferable carbonconcentration is 5×10¹⁵ to 3×10¹⁷ atoms/cm³.

The preferable remaining oxygen concentration in the wafer is 6.5×10¹⁷atoms/cm³ (Old-ASTM) or more. When this is less than 6.5×10¹⁷ atoms/cm³,the mechanical strength is lowered. Although an upper limit of theremaining oxygen concentration is not especially defined, it ispreferably 25×10¹⁷ atoms/cm³ or less in view of concern of defectgeneration on the substrate surface because of excessive oxygenprecipitate depending on a device heat treatment condition which is tobe implemented on the side of the user because the oxygen precipitate isincreased as the oxygen concentration is increased, or a limit of aninitial oxygen concentration as will be described below. According to anespecially preferable remaining oxygen concentration, its lower limit isbeyond 8×10¹⁷ atoms/cm³ and its upper limit is 20×10¹⁷ atoms/cm³ or lessand more preferably, 16×10¹⁷ atoms/cm³ or less.

The high-resistance silicon wafer of the present invention can be anytype. The type will be illustrated below.

{circumflex over (1)} Although it is thought that an appropriate amountof oxygen precipitate is effective in providing the gettering ability inthe high-resistance silicon wafer of the present invention, the oxygenprecipitate could become a harmful defect in the device formation on theother hand and especially the oxygen precipitate existing on the surfacelayer of the wafer causes deterioration of the device characteristics.Therefore, it is desirable that the oxygen precipitate is eliminatedfrom the surface layer of the wafer at least. In this respect, thepresent invention can be applied to a DZ wafer on which DZ (DenudedZone) is formed in depth of at least 5 μm or more from a wafer surface.

The DZ layer can be formed by OD (Oxygen Out-Diffusion) treatment. TheOD treatment is preferably performed at 1100 to 1350° C. for 1 to 5hours. Since the OD treatment is performed at high temperature such as1100° C. or higher, it can be used also as the heat treatment which iseffective in preventing the generation of the oxygen donor. In addition,by selecting a gas atmosphere in the OD treatment, a grown-in defectsuch as COP (Crystal Originated Particle: holes which are a void defectsurrounded by (111) surface) can be eliminated from the wafer surfacelayer.

That is, as the gas atmosphere in the OD treatment, there are nitrogengas, oxygen gas, hydrogen gas, argon gas and the like. The COP can beeliminated from the wafer surface layer in the atmosphere of thehydrogen gas, the argon gas and the mixture of these gas among the aboveOD treatment atmosphere. This is an effective processing for a waferwhich is not free of the COP.

For reference, the DZ layer is formed such that after a heat treatmentat 1000° C. for 16 hours in a dry oxygen atmosphere, a wafer is cleavedand a wafer cleaved face is etched away by 2 μm with a selected etchingsolution (HF:HNO₃:CrO₃:Cu(NO₃)₂:H₂O:CH₃COOH=1200 cc:600 cc:250 g:40g:1700 cc:1200 cc). Then, it is defined by a distance from the wafersurface to a first etch pit by an optical microscope.

{circumflex over (2)} There is a high-speed temperature rising andfalling RTA (Rapid Thermal Anneal) treatment called lamp annealtreatment also as a heat treatment which is similar to the OD treatment.The present invention is effective in the wafer which receives thistreatment and the treatment can be used also as the heat treatment whichis effective in preventing the generation of the oxygen donor.

{circumflex over (3)} Apart from the above heat treatment, an IG(Intrinsic Getterring) treatment which aggressively forms the oxygenprecipitate is performed in some cases in order to provide the getteringability. Although the IG treatment is a heat treatment for forming theoxygen precipitate nucleus, a heat treatment for growing an oxygenprecipitate is performed subsequently in some cases. Since the heattreatment for growing the oxygen precipitate is a heat treatment forconsuming oxygen in the wafer as the oxygen precipitate is grown, it iseffective in preventing the generation of the oxygen donor. However, itis necessary to note that the oxygen concentration in the wafer is notlowered to 6.5×10¹⁷ atoms/cm³ or less.

{circumflex over (4)} From the same viewpoint, the present invention iseffective in an epitaxial wafer in which an epitaxial layer is formed ona wafer surface. In manufacturing the epitaxial wafer, a hydrogen bakingtreatment at 1100° C. or more is performed prior to an epitaxial growingtreatment at about 1100° C. These heat treatments can be used also asthe heat treatment which is effective in preventing the generation ofthe oxygen donor.

{circumflex over (5)} From the same viewpoint, the present invention iseffective in a base wafer of an SOI wafer. The SOI wafer may be either abonded type or an SIMOX type. In manufacturing the bonded type of wafer,a high-temperature heat treatment at 1100° C. or more is performed in astep of bonding the wafer. This high-temperature heat treatment can beused also as the heat treatment which is effective in preventing thegeneration of the oxygen donor. Meanwhile, in manufacturing the SIMOXtype, a high-temperature heat treatment at 1100° C. or higher isperformed in order to form a BOX layer after oxygen ion injection. Thishigh-temperature heat treatment can be used also as the heat treatmentwhich is effective in preventing the generation of the oxygen donor.

{circumflex over (6)} Although defect distribution of the wafer in thethickness direction of the wafer was focused on in the above, the wafercan be classified by defect distribution in the diameter direction ofthe wafer. The present invention can be effective in a normal wafer inwhich the COP exists at least in a part in the diameter direction aswell as a wafer free of the COP, which is provided from a defect-freecrystal in which the Grown-in defect such as a large-sized COP ordislocation cluster is eliminated from an entire region in the crystaldiameter direction by an operation and the like in a crystal pullingprocess.

{circumflex over (7)} Referring to the COP-free wafer, although it wasdescribed in the OD treatment, the present invention can be effective innot only the COP-free wafer provided from the defect-free crystal butalso a COP-free annealed wafer in which the COP is eliminated from asurface layer by a heat treatment at 1100° C. for 1 hour in thenon-oxidizing gas atmosphere.

This annealing can be used also as the heat treatment which is effectivein preventing the generation of the oxygen donor. In addition, theCOP-free wafer means a state in which a density of LPD (Light PointDefect) having a size 0.12 μm or more and observed on the wafer surfaceis controlled so as to be 0.2/cm² or less.

According to the manufacturing method of the high-resistance siliconwafer of the present invention, since the carbon concentration in thewafer is 5×10¹⁵ to 5×10¹⁷ atoms/cm³, the oxygen donor, especially thethermal donor can be effectively prevented from being generated whilethe remaining oxygen concentration is maintained at high level. Inaddition, when the heat treatment at 1100° C. or higher is performed inaddition to the carbon doping, not only the thermal donor but also thenew donor can be effectively prevented from being generated, so that theresistivity can be stabilized by both of them.

The initial oxygen concentration (oxygen concentration before the heattreatment) in the silicon wafer is selected from a range such that theremaining oxygen concentration becomes 6.5×10¹⁷ atoms/cm³ or more(Old-ASTM) in view of the generation amount of the BMD. Quantitatively,considering that there is a case where the BMD is not generated, it ispreferably beyond 8×10¹⁷ atoms/cm³, and more preferably 10×10¹⁷atoms/cm³ or more. According to an upper limit of the initial oxygenconcentration, in view of solid solution limit of oxygen and excessiveoxygen precipitate as will be described below, it is preferably 25×10¹⁷atoms/cm³ or less, and more preferably 20×10¹⁷ atoms/cm³ or less, andfurther preferably 18×10¹⁷ atoms/cm³ or less. When the oxygenconcentration is extremely high, since the oxygen precipitate isexcessively generated, a secondary defect such as a defect in the oxygenprecipitate or in a laminated layer or dislocation is generated in adevice active layer of the wafer surface layer, which deteriorates thedevice characteristics. However, since the oxygen precipitationtreatment is not performed in some cases, the upper limit can be allowedto be until 25×10¹⁷ atoms/cm³.

The remaining oxygen concentration after the heat treatment ispreferably not less than 6.5×10¹⁷ atoms/cm³ and not more than 25×10¹⁷atoms/cm³ (Old-ASTM) for the reason described above. In this case also,since some users do not care about the oxygen precipitate, the upperlimit is allowed to be until 25×10¹⁷ atoms/cm³.

The CZ silicon wafer receives various kinds of heat treatments which ispeculiar to its type. These existing heat treatments such as the oxygenout-diffusion heat treatment, the RTA treatment, the SIMOX heattreatment, the bonding heat treatment, the COP elimination annealingwhich are peculiar to the wafer type can be used also as the heattreatment which can be effective in preventing the generation of theoxygen donor as described above.

Furthermore, in addition to the existing heat treatment which ispeculiar to the wafer type, an exclusive treatment which is effective inpreventing the generation of the oxygen donor is also effective. Inaddition, the heat treatment for forming the oxygen precipitate nucleusto generate the oxygen precipitate and also the heat treatment forgrowing the oxygen precipitate can be implemented exclusively orcommonly.

The oxygen out-diffusion heat treatment is preferably performed at 1100to 1350° C. for 1 to 5 hours. The oxygen is reduced in the wafer surfacelayer by the oxygen out-diffusion heat treatment and since the oxygenprecipitate is prevented from being generated and grown, the DZ layer isformed. Furthermore, the oxygen donor is prevented from being generated.

The high-temperature oxidation heat treatment for forming the BOX layerin manufacturing the SIMOX wafer is normally performed at 1250 to 1400°C. for 1 to 20 hours. The heat treatment atmosphere in the treatmentcomprises oxygen gas, argon gas or mixture of these.

When the bonded wafer is manufactured, after a thermally oxidized filmhaving a desired film thickness is formed on the surface of the supportsubstrate, the oxidation treatment is performed at 1100° C. or higher inorder to bond the support substrate and the active layer substrate. Thisheat treatment is also effective in preventing the generation of theoxygen donor.

According to the COP elimination annealing, the COP can be sufficientlyeliminated in the heat treatment performed at 1100° C. or higher for 1hour or more in a non-oxidizing gas atmosphere and the heat treatmentcan be used also as the heat treatment which is effective in preventingthe generation of the oxygen donor. More specifically, as the heattreatment atmosphere, a hydrogen gas atmosphere, an argon gas atmosphereor an atmosphere of mixture of these gas is preferable, and the heattreatment is preferably performed at 1150 to 1200° C. for 1 to 5 hours.If the temperature is less than 1110° C. and the time is less than 1hour, the oxygen donor is not sufficiently prevented from beinggenerated. Meanwhile, if the temperature is beyond 1350° C., the slipdislocation is likely to be generated, so that the heat treatment isdesirably performed within 5 hours in view of productivity.

In the IG treatment for providing the gettering ability, the heattreatment for generating the oxygen precipitate nucleus is preferablyperformed at relatively low temperature such as 550 to 950° C. for 1 to16 hours, and the heat treatment for growing the oxygen precipitate ispreferably performed at high temperature such as 900 to 1100° C. for 1to 20 hours. The latter heat treatment for growing the oxygenprecipitate is effective in preventing the generation of the oxygendonor.

As described above, in the high-resistance silicon wafer according tothe present invention, while the generation of the oxygen thermal donorcan be prevented by the carbon doping, the generation of the oxygendonor can be effectively prevented in many kinds of wafers by usingvarious kinds of heat treatments which are peculiar to the wafer typewithout using any special operation. Therefore, the generation of thethermal donor and the new donor can be prevented only by carbon dopingsubstantially. As a result, lowering of unstable resistivity because ofthe generation of the oxygen donor can be prevented with extremelyeconomical efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing an influence of an oxygen donor on resistivityof a wafer.

FIG. 2 is a graph showing an influence of carbon doping on generation ofthe oxygen donor.

FIG. 3 is a graph showing an influence of a heat treatment on generationof the oxygen donor in a carbon doped product.

FIG. 4( a) to 4(c) are graphs each showing an influence of the kind ofheat treatments on the generation of the oxygen donor in a carbon dopedproduct.

FIGS. 5( a) and 5(b) are graphs each showing an influence of a remainingoxygen concentration on the generation of the oxygen donor in a carbonnon-doped product.

FIG. 6 is a graph showing an influence of hydro annealing on thegeneration of the oxygen donor in the carbon doped wafer and the carbonnon-doped wafer.

FIG. 7 is a graph showing an influence of a temperature and a time onthe generation of the oxygen donor when various kinds of non-oxidizinggas are used in the heat treatment of the carbon doped product.

FIG. 8 is a graph showing an influence of a high-temperature heattreatment for forming a BOX layer in a manufacturing process of a SIMOXwafer on the generation of the oxygen donor in the carbon doped waferand the carbon non-doped wafer.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, first to fourth embodiments of the present invention willbe described.

First Embodiment DZ Wafer

As the first step, a high-oxygen, high-resistance and carbon-dopedsilicon single crystal is formed by a normal CZ method. As the secondstep, a primary substrate in which for example, an amount of oxygen is10 to 18×10¹⁷ atoms/cm³, an amount of carbon is 5×10¹⁵ to 5×10¹⁷atoms/cm³ and resistance is high (100 Ωcm or more) is formed from thesilicon single crystal.

As the third step, an OD treatment is performed on the primary substrateat 1100 to 1200° C. for 1 to 4 hours. By this OD treatment, an oxygenprecipitate (BMD) is prevented from being generated in the vicinity of awafer surface in the heat treatment as will be described below. Thus, aDZ (Denuded Zone) layer is formed at least 5 μm or more in depth from asurface of a product wafer.

The OD treatment can be performed in an atmosphere of a mixed gas ofnitrogen gas and oxygen gas. In addition, it can be performed in ahydrogen gas atmosphere. Furthermore, it can be performed in argon gasatmosphere. Still in addition, it can be performed in an atmosphere of amixed gas of hydrogen gas and argon gas.

As the fourth step, a heat treatment for forming a nucleus of the oxygenprecipitate is performed on the primary substrate at 550 to 950° C. for1 hour or more. It is performed at 700° C. or more preferably. Then, asa heat treatment for growing the oxygen precipitate, a heat treatment isperformed at 900 to 1100° C. for 1 hour or more.

By the heat treatment at the fourth step, the oxygen precipitate (BMD)is formed at a density of 1×10⁴ pieces/cm² or more in a silicon waferhaving high resistance of 100 Ωcm or more. Thus, the oxygenconcentration in the wafer is reduced, for example, to be not less than6.5×10¹⁷ atoms/cm³ and not more than 16×10¹⁷ atoms/cm³.

The silicon wafer product as thus manufactured is shipped to a devicemanufacturer. The characteristics of the product are described below.

First, since a general-purpose silicon wafer having a relatively highoxygen concentration is used as the primary substrate, it iseconomically efficient. Secondly, since the oxygen precipitate iseliminated from the wafer surface layer, it is superior in devicecharacteristics. Thirdly, since the large-sized oxygen precipitate (BMD)is formed in the wafer at a high density, it is superior in getteringability. Fourthly, since a final oxygen concentration is relatively highand carbon is doped, it is superior in mechanical strength and slippingresistance. Fifthly, because of an inhibitory action of oxygen thermaldonor by the doped carbon and an inhibitory action of oxygen donor byvarious kinds of high-temperature heat treatment in the wafermanufacturing process, although the final oxygen concentration is at arelatively high level, a resistance value is prevented from being variedunstably because of generation of the oxygen donor in a heat treatmentfor forming a circuit which is to be performed on the side of the devicemanufacturer.

In addition, when a hydrogen gas or an argon gas is selected as theatmosphere in the OD treatment, a grown-in defect can be reduced orvanished and a density of a LPD (Light Point Defect) having a size of0.12 μm or more observed on the wafer surface can be reduced to 0.2pieces/cm² or less.

Second Embodiment Epitaxial Wafer

As the first step, a high-oxygen, high-resistance and carbon-dopedsilicon single crystal is formed by a normal CZ method. As the secondstep, a primary substrate in which for example, an amount of oxygen is10 to 18×10¹⁷ atoms/cm³ or more, an amount of carbon is 5×10¹⁵ to 5×10¹⁷atoms/cm³ and resistance is high (100 Ωcm or more) is formed from thesilicon single crystal.

As the third step, an OD treatment is performed on the primary substrateat 1100 to 1200° C. for 1 to 4 hours. As the fourth step, a heattreatment for forming an oxygen precipitate nucleus is performed under acondition of at 550 to 950° C. for 1 hour or more. As the fifth step, aheat treatment is performed at 900 to 1100° C. for 1 hour or more as aheat treatment for forming a nucleus of the oxygen precipitate and as aheat treatment for growing the oxygen precipitate.

As the sixth step, after a hydrogen baking process at about 1180° C. isperformed on each substrate processed until the second step, processeduntil the third step, processed until the forth step, or processed untilthe fifth step, an epitaxial growth process for growing an epitaxiallayer having a thickness 5 μm is performed at about 1130° C.

An epitaxial silicon wafer product as thus manufactured has thefollowing characteristics.

In order to examine whether the oxygen donor such as thermal donor (TD)and new donor (ND)is prevented from being generated or not, a heattreatment for generating the thermal donor is performed at 400° C. for 2hours and a heat treatment for generating the new donor is performed at750° C. for 8 hours on the respective wafers. There is no oxygen donorformed in the wafer on which epitaxial layer is grown at any step.

Especially, according to the wafer on which the epitaxial layer is grownafter the second step, it is most superior in cost and it is effectiveas an epitaxial silicon wafer in which resistivity is not varied bygeneration of the oxygen donor even through the heat treatment of thedevice process.

In addition, according to the wafer on which the epitaxial layer isgrown after the third step, since oxygen on the surface of the substrateis dispersed outward, the BMD is not precipitated on the surface of thesubstrate during the epitaxial growing process or the heat treatment ofthe device process, so that it is effective as a high-definitionepitaxial silicon wafer in which the generation of a defect due to theBMD precipitation does not offur in the epitaxial layer BMD isprecipitated.

In addition, according to the wafer on which the epitaxial layer isgrown in the fourth step, since the DZ layer is also formed and oxygenprecipitate nucleus sufficiently exists in the wafer, when it is used inthe device process including a heat treatment at high temperature for along time, it can be expected that the oxygen precipitate issufficiently grown by the heat treatment of the device process, so thatit is effective as a epitaxial silicon wafer which is superior in agettering ability.

Furthermore, according to the wafer on which the epitaxial layer isgrown in the fifth step, since the DZ layer is also formed and the BMDhas been already sufficiently grown, it is effective as a epitaxialsilicon wafer which provides enough gettering ability from an initialstage of the device process.

Thus, according to each of the wafer on which the epitaxial layer isgrown after each step, it is needless to say that variation in aresistance value because of generation of the oxygen donor in the heattreatment for forming the circuit which is to be performed on the sideof the device manufacturer can be avoided.

Third Embodiment SIMOX Wafer

As the first step, a high-oxygen, high-resistance and carbon-dopedsilicon single crystal is formed by a normal CZ method. As the secondstep, a primary substrate in which for example, an amount of oxygen is10 to 18×10¹⁷ atoms/cm³ or more, an amount of carbon is 5×10¹⁵ to 5×10¹⁷atoms/cm³ and resistance is high (100 Ωcm or more) is formed from thesilicon single crystal.

As the third step, oxygen ions are accelerated to 30 to 200 keV and ioninjection is performed in a surface of the primary substrate at adensity of about 10¹⁸ atoms/cm³. As the fourth step, a heat treatment isperformed on the substrate provided at the third step at 1250 to 1400°C. for 1 to 20 hours in an atmosphere of oxygen gas or argon gas ormixed oxygen and argon gas, to form a BOX layer (buried oxide filmlayer) in the substrate.

The SIMOX wafer product as thus manufactured has followingcharacteristics.

Since a general-purpose silicon wafer having a relatively high oxygenconcentration is used as a primary substrate, it is superior ineconomical efficiency. Since a final oxygen concentration is relativelyhigh and carbon is doped, it is superior in mechanical strength andslipping resistance. Because of an inhibitory action of oxygen thermaldonor by the doped carbon and an inhibitory action of oxygen donor byvarious kinds of high-temperature heat treatments in the wafermanufacturing process, although the final oxygen concentration is at arelatively high level, a resistance value is prevented from being variedunstably because of generation of the oxygen donor in the heat treatmentfor forming the circuit which is to be performed on the side of thedevice manufacturer.

Fourth Embodiment Bonded Wafer

As the first step, a high-oxygen, high-resistance and carbon-dopedsilicon single crystal is formed by a normal CZ method. As the secondstep, a primary substrate in which for example, an amount of oxygen is10 to 18×10¹⁷ atoms/cm³ or more, an amount of carbon is 5×10¹⁵ to 5×10¹⁷atoms/cm³ and resistance is high (100 Ωcm or more) is formed from thesilicon single crystal.

As the third step, although it depends on a manufacturing method of abonded SOI wafer, a heat treatment is performed at about 1000° C. in anatmosphere of oxygen in a series of wafer manufacturing steps and athermally oxidized film serving as a BOX oxide film is formed on thesurface of the primary substrate.

As the fourth step, the above primary substrate as a support substrateis bonded to another substrate serving as an active layer by heattreatment of about 1150° C. In addition, in a case a thick SOI wafer ismanufactured, as another substrate serving as the active layer, ahigh-resistance silicon substrate which is doped with carbon may be usedsimilar to the support substrate.

As the fifth step, the wafer on the side of the active layer is groundand etched to a thickness 0.5 μm.

The bonded SOI wafer product as thus manufactured has the followingcharacteristics.

Since a general-purpose silicon wafer having a relatively high oxygenconcentration is used as a primary substrate, it is superior ineconomical efficiency. Since a final oxygen concentration is relativelyhigh and carbon is doped, it is superior in mechanical strength andslipping resistance. Because of an inhibitory action of oxygen thermaldonor by the doped carbon and an inhibitory action of oxygen donor byvarious kinds of high-temperature heat treatments, although the finaloxygen concentration is at a relatively high level, a resistance valueis prevented from being varied unstably because of generation of theoxygen donor in the heat treatment for forming the circuit which is tobe performed on the side of the device manufacturer.

Then, working examples of the present invention will be shown andcompared with comparative examples to clarify the effect of the presentinvention.

FIRST WORKING EXAMPLE

The following two kinds of 8-inch sample wafers were cut out from asilicon single crystal grown by the CZ method. The first sample wafer isa P type carbon non-doped product in which resistivity is 1000 Ωcm andan oxygen concentration is 5×10¹⁷ atoms/cm³. The second sample wafer isa P type carbon doped product in which resistivity is 1000 Ωcm, anoxygen concentration is 5×10¹⁷ atoms/cm³, and a carbon concentration is1×10¹⁶ atoms/cm³.

A heat treatment for eliminating the oxygen donor (DK treatment) wasperformed on both wafers at 650° C. for 30 minutes and then thefollowing three patterns of heat treatments were performed. According tothe first pattern, only an OD treatment was performed at 1150° C. for3.5 hours in a nitrogen atmosphere containing 3% of oxygen. According tothe second pattern, after the OD treatment, an isothermal heat treatmentwas performed at 700° C. for 1 to 8 hours or 750° C. for 2 to 16 hoursin the nitrogen atmosphere containing 3% of oxygen as a heat treatmentfor forming oxygen precipitate nucleus. According to the third pattern,after the isothermal heat treatment, a high-temperature heat treatmentwas further performed at 1000° C. for 16 hours in the nitrogenatmosphere as a heat treatment for growing the oxygen precipitate.

Then, a heat treatment for generating a thermal donor was performed onthe carbon non-doped wafer and the carbon doped wafer on which the DKtreatment was performed (subsequent heat treatment was not performed) at400° C. for 1 to 4 hours in the nitrogen atmosphere. After the heattreatment, an oxygen donor density was measured in such a manner thatresistivity was measured by using a 4-probe method and an amount ofoxygen donor was found from a difference between the resistivities afterthe DK treatment. The result is shown in FIG. 2. It is shown that theoxygen donor is prevented from being generated by the carbon dopingonly. Especially, until the treatment at 400° C. for 2 hours, the oxygendonor is prevented from being generated on the carbon doped wafer ascompared with the carbon non-doped wafer.

The result after the second pattern of heat treatment was performed onthe carbon doped wafer is shown in FIG. 3. The isothermal heat treatmentat 700° C. for 1 to 8 hours or at 750° C. for 2 to 16 hours is the heattreatment for forming the oxygen precipitate nucleus, and also the heattreatment for generating a new donor. When the OD treatment at 1150° C.for 3.5 hours is performed, the oxygen donor is prevented from beinggenerated after the isothermal heat treatment.

After each heat treatment of the first, second and third patterns wasperformed on the carbon doped wafer, a heat treatment for generating thethermal donor was performed on each wafer at 400° C. for 1 to 4 hours inthe nitrogen atmosphere. The result from measurement of an oxygen donordensity after the heat treatment for generating the thermal donor wasshown in FIG. 4( a) to 4(c).

As can be seen from comparison between FIG. 4( a) or 4(b) and FIG. 2,the oxygen donor is more prevented from being generated until the heattreatment at 400° C. for 2 hours by the OD treatment at 1150° C. for 3.5hours or the subsequent heat treatment for generating the oxygenprecipitate nucleus at 750° C. As shown in FIG. 4( c), thehigh-temperature heat treatment at 1000° C. for 16 hours as the heattreatment for growing the oxygen precipitate is more effective inpreventing the oxygen donor generation and its effectiveness is notinfluenced by the remaining oxygen concentration.

For reference, the result when the third heat treatment was performed onthe carbon non-doped wafer is shown in FIG. 5( a) and 5(b). As shown inFIG. 5( a), when the OD treatment is performed, the remaining oxygenconcentration is not sufficiently lowered even if the treatment time atthe isothermal heat treatment is increased, and it is difficult toprevent the oxygen thermal donor from being generated. In addition, asshown in FIG. 5( b), when the OD treatment is not performed, theremaining oxygen concentration is lowered (the oxygen precipitate isincreased) as the treatment time in the isothermal heat treatment isincreased and accordingly the oxygen donor is prevented from beinggenerated, but its effect is not so much as the effect provided by thecarbon doping shown in FIG. 4( c). In addition, since the DZ layer isnot provided by the heat treatment without the OD treatment, it cannotbe applied to the device.

In order to provide the same effect as the effect by the carbon dopingshown in FIG. 4( c) by generation of the oxygen precipitate in the heattreatment including the OD treatment, the OD treatment was performed onthe carbon non-doped wafer having an initial oxygen concentration of15×10¹⁷ atoms/cm³ and the heat treatments at 700° C. for 64 hours and at1000° C. for 16 hours were performed. However, the remaining oxygenconcentration is only lowered to 12×10¹⁷ atoms/cm³ and the oxygenthermal donor is not sufficiently prevented from being generated, sothat a further long time unrealistic heat treatment is needed.

In the device process, a sintering heat treatment is performed at 400°C. or 350° C. for about 30 minutes after a wiring process of metal suchas Al or Cu. This metal wiring is laminated to be several layers and theabove described heat treatment is performed on each layer. Therefore,even when the heat treatment at 400° C. for about 2 hours is performed,it is necessary to maintain resistivity which is 100 Ωcm or more andpreferably 1000 Ωcm or more. Since there is a measurement error in the4-probe measurement, in the case of the p type after the DK treatment, avalue lower than the resistance value is provided in some cases. Itsvariation is within 5×10¹² atoms/cm³ in terms of a donor amount.

SECOND WORKING EXAMPLE

The following 5 kinds of 8-inch sample wafers were cut out from asilicon single crystal grown by the CZ method. The first sample wafer isa P type carbon non-doped product in which resistivity is 1000 Ωcm andan oxygen concentration is 15×10¹⁷ atoms/cm³. The second to fifth samplewafers are P type carbon doped products in which resistivity is 1000Ωcm, an oxygen concentration is 15×10¹⁷ atoms/cm³, and a carbonconcentration is 5×10¹⁵, 1×10¹⁶, 5×10¹⁶, 1×10¹⁷ atoms/cm³.

A heat treatment for eliminating the oxygen donor (DK treatment) wasperformed on each of the above wafers at 650° C. for 30 minutes and thenthe OD treatment was performed at 1150° C. for 3.5 hours in a nitrogenatmosphere containing 3% of oxygen. Then, an isothermal heat treatmentwas performed in a nitrogen atmosphere containing 3% of oxygen as a heattreatment for forming oxygen precipitate nucleus at 700° C. for 8 hourson the carbon non-doped wafer and at 750° C. for 2 hours on the carbondoped wafer, and then, a high-temperature heat treatment was performedon these wafers in the nitrogen atmosphere as a heat treatment forgrowing the oxygen precipitate at 1000° C. for 16 hours.

A heat treatment for generating the oxygen thermal donor was performedat 400° C. for 4 hours in the nitrogen atmosphere on each of the DZ-IGprocessed wafer. An amount of oxygen donors was calculated from theresult from measurement of resistivity of each wafer after the heattreatment. In case of the carbon doped wafer, variation in resistivityis small and the amount of oxygen donors is within an allowable range,meanwhile in the case of the carbon non-doped wafer, the oxygen donorsare generated beyond the allowable value. As the result, it is foundthat the oxygen donor is effectively prevented from being generated whenthe carbon concentration is 5×10¹⁵ atoms/cm³ or more.

THIRD WORKING EXAMPLE

The following 2 kinds of 8-inch sample wafers were cut out from asilicon single crystal grown by the CZ method. The first sample wafer isa P type carbon non-doped product in which resistivity is 1000 Ωcm andan oxygen concentration is 15×10¹⁷ atoms/cm³. The second sample wafer isa P type carbon doped product in which resistivity is 1000 Ωcm, anoxygen concentration is 15×10¹⁷ atoms/cm³, and carbon concentration is1×10¹⁶ atoms/cm³.

These wafers were annealed with hydrogen in a hydrogen atmosphere at1200° C. for 1 hour. An oxygen donor amount was found by measuringresistivity after the heat treatment for generating the thermal donorwas performed at 400° C. for 4 hours in the nitrogen atmosphere justafter the annealing. The result of oxygen donor amount thus obtained isshown in FIG. 6. The variation in resistivity is small and the amount ofoxygen donor is not more than an allowable value in each wafer justafter the annealing. Although the amount of oxygen donor generated inthe carbon doped wafer is also not more than the allowable value afterthe heat treatment at 400° C. for 4 hours, the amount was not less thanthe allowable value in the case of the carbon non-doped wafer. As theresult, it is found that the existing heat treatment of hydrogenannealing on the carbon doped wafer can serve also as the heat treatmentwhich is effective in preventing the generation of the oxygen donor.

In addition, in order to find an effective temperature and a time of thehydrogen annealing, the carbon doped wafer was annealed with hydrogen at800 to 1150° C. for 1 to 4 hours. Then, a heat treatment was performedat 1200° C. for 1 hour in an atmosphere of argon gas and an atmosphereof mixture gas of argon gas and hydrogen gas besides in the hydrogen gasatmosphere. The used wafers were both the second sample wafers. Afterthe heat treatment, the heat treatment for generating the oxygen donorwas performed on each wafer in the nitrogen atmosphere at 450° C. inwhich the oxygen donor is likely to be generated more than at 400° C.,changing the time for 1 hour, 2 hours and 4 hours. The resistivity ofeach wafer after the heat treatment was measured and an amount of oxygendonor generated was found from the above result. The oxygen donor amountis shown in FIG. 7.

As can be clear from FIG. 7, although the oxygen donor was generatedbeyond the allowable value until the heat treatment at 1000° C. for 1hour, the amount of oxygen donor generated was not more than theallowable value at 1100° C. or more for 1 hour or more. In addition,when the heat treatment was performed at 1200° C. for 1 hour in theargon gas atmosphere and in the atmosphere of the mixture gas of argongas and hydrogen gas, the amount of oxygen donor generated is not morethan the allowable value. That is, it is found that the oxygen donor canbe effectively prevented from being generated when the heat treatment isperformed at 1100° C. or more for 1 hour or more in a non-oxidizing gasatmosphere.

FOURTH WORKING EXAMPLE

A 8-inch wafer was cut out from a silicon single crystal grown by the CZmethod. The wafer is a P type wafer in which resistivity is 2000 Ωcm, anoxygen concentration is 15×10¹⁷ atoms/cm³, and a carbon concentration is1×10¹⁶ atoms/cm³.

The heat treatment for eliminating the oxygen donor (DK treatment) wasperformed on the wafer at 650° C. for 30 minutes and then the followingheat treatment was performed. First, the OD treatment was performed at1150° C. for 3.5 hours in the nitrogen atmosphere containing 3% ofoxygen, and then the heat treatment for forming the oxygen precipitatenucleus was performed at 750° C. for 2 hours in the similar atmosphere.Then, epitaxial growing treatment was performed on the wafer so as toprovide a P type layer having resistivity 10 Ωcm and a thickness 5 μm.

Even when the heat treatment for generating the thermal donor wasperformed at 400° C. for 2 hours and the heat treatment for generatingthe new donor was performed at 750° C. for 8 hours on this epitaxialwafer, the resistivity of the substrate is maintained at 2000 Ωcm ormore which is the same as that after the DK treatment.

FIFTH WORKING EXAMPLE

The following 2 kinds of 8-inch sample wafers were cut out from asilicon single crystal grown by the CZ method. The first sample wafer isa P type carbon non-doped product in which resistivity is 1000 Ωcm andan oxygen concentration is 15×10¹⁷ atoms/cm³. The second sample wafer isa P type carbon doped product in which resistivity is 1000 Ωcm, anoxygen concentration is 15×10¹⁷ atoms/cm³, and a carbon concentration is1×10¹⁶ atoms/cm³.

After the heat treatment for eliminating the oxygen donor (DK treatment)was performed on both wafer at 650° C. for 30 minutes, oxygen ions weresputtered into the surface at an acceleration voltage 100 keV. Then, thesubstrate was put in a heat treatment furnace which is maintained at700° C. Then, the furnace was heated up to 1320° C. and kept for 10hours. Then, the substrate was cooled down at 700° C. and taken out ofthe furnace, whereby an SIMOX wafer was manufactured.

The heat treatment for generating the thermal donor was performed at400° C. for 4 hours in the nitrogen atmosphere on the SIMOX wafers whichwas manufactured from the carbon doped wafer and the carbon non-dopedwafer. The result from the measurement of the oxygen donor density afterthe heat treatment for generating the thermal donor is shown in FIG. 8.As shown in FIG. 8, the oxygen donor is prevented from being generatedin the carbon-doped SIMOX wafer. Meanwhile, although the generation ofthe oxygen donor is prevented a little in the carbon non-doped SIMOXwafer, its effect is not so much as the effect in the carbon-doped SIMOXwafer.

SIXTH WORKING EXAMPLE

The following 2 kinds of 8-inch sample wafers were cut out from asilicon single crystal grown by the CZ method. The first sample wafer isa P type carbon non-doped product in which resistivity is 1000 Ωcm andan oxygen concentration is 15×10¹⁷ atoms/cm³. The second sample wafer isa P type carbon doped product in which resistivity is 1000 Ωcm, anoxygen concentration is 15×10¹⁷ atoms/cm³, and a carbon concentration is1×10¹⁶ atoms/cm³.

After the heat treatment for eliminating the oxygen donor (DK treatment)was performed on each wafer at 650° C. for 30 minutes, the heattreatment was performed on each wafer at 1000° C. in the oxygenatmosphere to form the thermally oxidized film on the surface of theprimary substrate. Then, this substrate serving as a support substratewas bonded to another wafer serving as an active layer at 1150° C. Then,the wafer on the side of the active layer was ground and etched to athickness 0.5 μm, whereby a bonded SOI wafer was manufactured.

The heat treatment for generating the thermal donor was performed at400° C. for 4 hours in the nitrogen atmosphere on the bonded SOI waferswhich were manufactured with the carbon doped wafer and the carbonnon-doped wafer. An oxygen donor density was measured after the heattreatment for generating the thermal donor. Resistivity of the bondedcarbon-doped wafer was small in variation from the resistivity after theDK treatment and generation of the oxygen donor was prevented within anallowable range. Meanwhile, according to the bonded carbon non-dopedwafer, although the generation of the oxygen donor was prevented alittle, its effect was not so much as that in the bonded carbon dopedwafer.

INDUSTRIAL APPLICABILITY

As described above, according to the high-resistance silicon wafer ofthe present invention, generation of the oxygen donor can be preventedin the heat treatment for forming circuits which is to be performed onthe side of the device manufacturer by carbon doping without lowering aremaining oxygen concentration. Thus, the mechanical strength of thewafer can be maintained and heat treatment costs can be lowered.Furthermore, since an appropriate amount of oxygen precipitate isgenerated without being influenced by the remaining oxygenconcentration, an excellent gettering ability can be provided.

In addition, according to the manufacturing method of high-resistancesilicon wafer of the present invention, the generation of the oxygendonor can be effectively prevented by performing the heat treatmentwhich is effective in preventing the generation of the oxygen donor inaddition to the carbon doping. Furthermore, since various kinds of heattreatments which are peculiar to a wafer type can be used as the aboveheat treatment, an increase in heat treatment costs can be avoided andexcellent economical efficiency is provided.

1. A high-resistance silicon wafer having resistivity of 100 Ωcm ormore, wherein a carbon concentration is 5×10¹⁵ atoms/cm³, and wherein anoxygen concentration is over 8×10¹⁷ atoms/cm³ (Old-ASTM).
 2. Thehigh-resistance silicon wafer according to claim 1, wherein a DZ(Denuded Zone) layer is formed at least 5 μm or more in depth from asurface of the wafer.
 3. The high-resistance silicon wafer according toclaim 1, wherein a density of a LPD (Light Point Defect) having a sizeof 0.12 or more and observed on a surface of the wafter is controlled soas to be 02/cm² or less.
 4. An epitaxial wafer having a high-resistancesilicon wafer according to claim 1 as a base wafer.
 5. An SOI having ahigh-resistance silicon wafer according to claim 1 as a base wafer. 6.The SOI wafer according to claim 5, which is a bonded wafer or SIMOXwafer.
 7. A method of manufacturing a high-resistance silicon wafer,wherein a heat treatment which is effective in preventing an oxygendonor from being generated is performed on a silicon wafer having aresistivity of 100 Ωcm or more and a carbon concentration of 5×10¹⁵ to5×10¹⁷ atoms/cm³, so that a remaining oxygen concentration is said waferafter the heat treatment is 6.5×10¹⁴ atoms/cm³ (Old-ASTM) or more. 8.The method of manufacturing a high-resistance silicon wafer according toclaim 7, wherein the heat treatment is a high-temperature heat treatmentat 1100° C. or higher.
 9. The method for manufacturing a high-resistancesilicon wafer according to claim 7, wherein the heat treatment is anoxygen out-diffusion treatment for forming a DZ (Denuated Zone) layer ona wafer surface.
 10. The method of manufacturing a high-resistancesilicon wafer according to claim 9, wherein after the oxygenout-diffusion treatment a heat treatment for forming an oxygenprecipitate nucleus, or the heat treatment for forming the oxygenprecipitate nucleus and a heat treatment for growing an oxygenprecipitate are performed.
 11. The method of manufacturing ahigh-resistance silicon wafer according to claim 7, wherein the heattreatment is high-temperature annealing treatment for eliminating a COPwhich is a void defect caused by a hole from a wafer surface.
 12. Amethod of manufacturing an SOI wafer, comprising manufacturing an SIMOXtype of SOI wafer that comprises a high-resistance silicon wafer havingresistivity of 100 Ωcm or more and a carbon concentration of 5×10¹⁵ to5×10¹⁷ atoms/cm³, and an oxygen concentration of over 8×10¹⁷ atoms/cm³(Old-ASTM) as a base wafer.
 13. The method of manufacturing the SOIwafer according to claim 12, wherein the high-temperature heat treatmentfor forming a BOX layer in a SIMOX type of SOI wafer manufacturingprocess serves also as a heat treatment which is effective in preventinggeneration of an oxygen donor.
 14. A method of manufacturing an SOIwafer, comprising manufacturing a bonded type of SOI wafer thatcomprises a high-resistance silicon wafer having resistivity of 100 Ωcmor more and a carbon concentration of 5×10¹⁵ to 5×10¹⁷ atoms/cm³, and anoxygen concentration of over 8×10¹⁷ atoms/cm³ (Old-ASTM) as a basewafer.
 15. The method of manufacturing the SOI wafer according to claim14, wherein the high-temperature heat treatment performed in the bondedtype of SOI wafer manufacturing process serves also as a heat treatmentwhich is effective in preventing the generation of the oxygen donor.